The present disclosure relates to an appliance or a group or line of home appliances that are adapted to respond to a demand response signal from a utility and initiate a load shedding event in the appliance. More particularly, the disclosure is directed to an improved antenna design that provides optimal gain in order to effectively receive the demand response signal.
A module is typically located outside of the appliance and is adapted to receive the signal from the utility, home energy manager, or the like, and communicate with a controller or microcontroller in the appliance. Further development of the module will eventually incorporate or integrate the module into the home appliance. The module acts as an interface with the appliance in order to relay the demand response signal to the appliance microcontroller. Present systems use either a pigtail or a printed circuit board (PCB) antenna that resides within the module. If the antenna is inadequate, the load shed signal will not be recognized or will go unnoticed regardless of the signal strength of the transmitting system.
Built into the module is a radio that receives the transmission from the head end or meter (and from an equivalent device such as a neighborhood transmitter, home energy manager, gateway, etc.), that receives the signal from the utility and transfers the data to the individual module(s) associated with one or more appliances or other end point devices. Other end point devices include, for example, a thermostat that controls a HVAC system, pool pumps, valves, load switches, televisions, etc. which include a transceiver/receiver/emitter radio incorporated therein. The preferred communication protocol is either 900 MHz, 2.4 GHz, or in the FM broadcast band or a radio digital signal (RDS), although other frequencies can be used with equal success. One issue is the ability of the receiving device to consistently receive the signal from the head end when the module or receiver is surrounded by an appliance(s), walls, etc. that exist in residences. Two options for improving reception in the radio are, first, transmitting more power or, second, improving gain in the antenna and pre-amplifier sections.
Because the module is made to be as small as possible, printed circuit board (PCB) antennas are typically used due to their compact size. However, the decibel gain of these PCB antennas is limited. This, in turn, contributes to poor reception. The power of the transmitter, on the other hand, is sometimes limited by Federal Communication Commission rules, power consumption, cost control, and interference with other RF devices. Therefore, adding power at the transmission end is not as simple as one might anticipate and therefore cannot necessarily be relied upon as the solution to the poor reception problem.
Employing an external antenna to improve reception requires the designer to evaluate physical size and aesthetics. Moreover, if the receiver is internalized to the appliance, the appliance will need to incorporate an antenna design at a location that will provide optimal gain in order to effectively receive the demand response signal. Still further, the physical antenna shapes and lengths must be accommodated over a wide range of home appliances, for example, a refrigerator, range, microwave oven, laundry product (e.g., clothes washer or dryer), dishwasher, hot water heater, window air conditioner, etc. Accordingly, a need exists for effective antenna designs that do not add undue cost, and likewise do not adversely impact the aesthetics of the home appliance.